Multiplex broadcasting of audio-video programs with DTMF signals

ABSTRACT

A multiplex broadcasting system and a multiplex broadcast signal receiver for receiving multiplex broadcast signals. composes second broadcast information of multi-frequency signals each of a combination of one tone in a first frequency group of audio bands unrelated with each other in articulation and one tone in a second frequency group of audio bands unrelated with each other in articulation, and multiplexes the second broadcast information and main broadcast audio signals. The multiplex broadcast signal receiver includes a decoder for continuously monitoring the audio signal included in the received multiplex broadcast signal, detecting multi-frequency signals to identify the combination of the multi-frequency signals, a receiver for receiving the output of the decoder as second broadcast information, and a memory for storing the second broadcast information. The stored second broadcast information is used automatically for accessing a two-way program involving the viewers.

This is a division of application Ser. No. 08/355,132 filed Dec. 13,1994 now U.S. Pat. No. 5,649,284.

FIELD OF THE INVENTION

The present invention relates to a broadcasting system suitable forbroadcasting multiplex broadcast signals. More particularly, the presentinvention relates to a broadcasting system for transmitting secondaryinformation, such as telephone number data, which is associated withprimary information, such as a television broadcast signal, to areceiver capable of receiving such information. The receiver of thepresent invention is capable of utilizing received secondary informationto initiate communications with a predetermined remote station.

BACKGROUND OF THE INVENTION

When broadcasting TV programs involving TV viewers and requestingresponses from TV viewers by telephone, facsimile or the like, such asquiz programs, debating programs, telephone order programs, ticketbooking programs, questionnaire programs and fund-raising campaignprograms, the broadcasting side often superimposes information for theTV viewers, such as the reception phone number and the account number ofthe remittee over pictures displayed on the screen for a certain periodof time or explains the information by speeches. However, since theinformation is broadcast in pictures or speeches for a fixed period oftime, the TV viewers need to write the information down to keep theinformation, such as the phone number and such.

If the TV receiver has a picture-in-picture function and a stillsubscreen function, i.e., a function to display a picture in asubscreen, the information, such as the phone number, can becontinuously displayed in a still picture on the still subscreen whenthe TV viewer selects the still subscreen function. However, the TVviewers must keep writing materials and a memo pad at hand and, even ifwriting materials and a memo pad are available, it is troublesome tomake a note of the information, the unfamiliar phone number and the likemay possibly be written down mistakenly or the notes may be lost.Furthermore, even if the TV receiver has a picture-in-picture function,the TV viewers often fail to set the TV receiver in a picture-in-picturemode in time due to delayed picture-in-picture mode setting operationand miss displaying the information.

Incidentally, an experimental two-way broadcasting service commonlyreferred to as EDS, or Extended Data Service, is being conducted inNorth America broadcasts, in most cases, information necessary forresponding to a broadcast program by a character multiplex broadcastingsystem, in which information is broadcast in a multiplex mode in thevacant horizontal blanking intervals of vertical blanking intervals,because the information has a large quantity of data including bit mapdata. However, the TV receiver needs a character multiplexing tunerhaving a complicated circuit configuration including a waveformequalizer and a data slicer to select character information frombroadcast TV signals and to decode the same. Accordingly, the TVreceiver equipped with such a character multiplex tuner is necessarilyexpensive and must be inevitably equipped with different circuits, forexample, for the NTSC broadcasting system, the BS broad casting system,the CS broadcasting system and the MUSE broadcasting system.

On the other hand, a TV receiver for receiving information, which isnecessary for responding to broadcast programs, broadcast in a two-waybroadcasting mode by a character multiplex broadcasting system used inJapan, the TV receiver must be equipped with a character multiplexbroadcast tuner provided with a large amount of Japanese font data tomeet the Broadcast Law. Therefore, TV receivers for domestic use aregenerally more expensive than those for export to Western countrieswhere the Japanese font data is typically not needed. Although Direct TVdata broadcasting service using one of the channels of satellitebroadcasting system is in an experimental stage in Japan, this datachannel can be used only by TV receivers equipped with a BS tuner.

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoing situationof the current multiplex broadcasting system and TV receivers and it istherefore an object of the present invention to provide a multiplexbroadcasting system capable of multiplexing a broadcast program andinformation about the broadcast program so that the receiving side isable to automatically select the information about the broadcast programfrom the received signals regardless of the broadcasting system by asimple, inexpensive circuit and to use the information easily andsurely, and a multiplex signal receiver for receiving multiplexbroadcast signals.

With the foregoing object in view, the present invention provides amethod of multiplex broadcasting main audio signals and secondarybroadcast information including the steps of composing the secondbroadcast information of multifrequency signals each of a combination ofone tone in a first frequency group of audio bands unrelated with eachother in articulation, and one tone in a second frequency group of audiobands unrelated with each other in articulation; and multiplexing themultifrequency signals and the main broadcast audio signals.

The present invention provides also a multiplex signal receiver forreceiving multiplex broadcast signals each produced by multiplexing amain broadcast audio signal, and second broadcast information composedof multifrequency signals each of a combination of one tone in a firstfrequency group of audio bands unrelated with each other in articulationand one tone in a second frequency group of audio bands unrelated witheach other in articulation, which includes a decoder for continuouslymonitoring the audio signal included in the received multiplex broadcastsignal, detecting the multifrequency signals, and decoding themultifrequency signals to identify the combination of the multifrequencysignals; a second broadcast information receiving means for receivingthe outputs of the decoding means as second broadcast information; andstorage means for storing the second broadcast information received bythe second broadcast information receiving means. The multi-frequencysignals each produced by combining one tone in a first frequency groupof audio bands unrelated with each other in articulation and one tone ina second frequency group of audio bands unrelated with each other inarticulation are well-known DTMF (dual tone multifrequency) signals. Thepresent invention uses DTMF signals for composing the second broadcastinformation, multiplexes the DTMF signals and the main audio signals toprovide multiplex broadcast signals, and receives the multiplexbroadcast signals. Encoders for encoding DTMF signals and decoders fordecoding DTMF signals are used widely in the related field, areinexpensive and are available on the market. Accordingly, transmittersand receivers for multiplex broadcasting can be fabricated at reducedcosts.

The present invention provides for a broadcast system in which secondaryinformation, such as telephone number or program schedule information,can be transmitted along with a primary broadcast signal, such as avideo/television signal. This secondary signal is multiplexed with theprimary signal to produce a multiplexed broadcast signal. The presentsystem incorporates a receiver for receiving the multiplexed broadcastsignal. This receiver includes a demultiplexer for separating thesecondary broadcast signal/information from the multiplexed broadcastsignal and a storage memory for storing data represented by thesecondary multiplexed broadcast signal. The receiver also includes atransmitter for communicating with a predetermined remote station. Thereis also provided in the receiver, a controller for accessing the datastored in the storage memory and utilizing it to initiate communicationswith a predetermined remote station via the transmitter. The receiveralso includes means for inputting data or command information.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following description takenin connection with the accompanying drawings, in which:

FIG. 1 is a block diagram of a multiplex broadcast receiver in apreferred embodiment according to the present invention and FIG. 1A is ablock diagram of a multiplex broadcast transmitter in a preferredembodiment according to the present invention;

FIG. 2 is a diagrammatic view of assistance in explaining DTMF signals;

FIG. 3 is a table of assistance in explaining conditions fortransmitting DTMF signals;

FIG. 4 is a flow chart of a signal receiving procedure for receivingsecond broadcast information of DTMF signals to be carried out by themultiplex broadcast receiver of FIG. 1;

FIG. 5 is a flow chart of a subroutine included in the signal receivingprocedure of FIG. 4; and

FIG. 6 is a flow chart of a responding procedure for responding to atwo-way broadcast program to be executed by the multiplex broadcastreceiver of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A multiplex broadcasting system and a multiplex broadcast receiverembodying the present invention will be described hereinafter on anassumption that multifrequency signals forming second broadcastinformation are DTMF signals.

In one embodiment of the present invention, a broadcasting stationtransmitts a multiplexed broadcast signal to a remote receiver. Themultiplexed broadcast signal is comprised of a primary broadcast signal,such as a video signal, which is multiplexed with a secondary broadcastsignal representing information, such as telephone number or programschedule & menu information, which is associated with the primarybroadcast signal. The multiplexed broadcast signal is transmitted andreceived by a receiver. The receiver then demultiplexes the secondarybroadcast signal information from the multiplexed broadcast signal andstores the data represented by the signal into a storage memory.Subsequently, this information is called up by a controller in thereceiver in response to a user input command from a user input means ofthe receiver. This information is then used by a transmitter within thereceiver to initiate communications with a predetermined remote stationspecified by the stored data. In one embodiment this stored datarepresents DTMF telephone number information and the transmitter is amodem device which is responsive to command signals from the controller.

A sending side, i.e., a broadcasting station multiplexes DTMF signalsrepresenting second broadcast information relating to a broadcastprogram, and main broadcast audio signals. A receiving side separatesthe DTMF signals from the received broadcast audio signals, decodes theDTMF signals to reproduce the second broadcast information, stores thereproduced second broadcast information, and uses the stored secondbroadcast information for telephone communication with a service stationor the like or for presetting a receiver for the future reception of adesired broadcast program.

DTMF Signals

Referring to FIG. 2, a DTMF signal system is an audio frequency bandsignal system that transmits a tone of a low-frequency group and a toneof a high-frequency group simultaneously. Each of the low-frequencygroup and the high-frequency group is comprised of tones in four audioband frequencies unrelated with each other in articulation. In the DTMFsignal system, the four frequencies of the low-frequency group are, forexample, 697 Hz, 770 Hz, 852 Hz and 941 Hz, and the four frequencies ofthe high-frequency group are, for example, 1209 Hz, 1336 Hz, 1477 Hz and1633 Hz. DTMF signals, i.e., combinations each of one of the frequenciesof the low-frequency group and one of the frequencies of thehigh-frequency group, are assigned respectively to push buttons "0" to"9", "A" to "D", "*" and "#" arranged in four rows and four columns asshown in FIG. 2. Hereinafter, the DTMF signals will be designated asfunction signals. Telephone communication uses the twelve functionsignals among the sixteen function signals in combination for expressingsubscribers' phone numbers (subscribers' addresses); that is, the twelvefunction signals are assigned to the numeric keys marked with "0" to "9"and the function keys marked with "*" and "#". The function signalscorresponding to the keys marked with characters "A", "B", "C" and "D"and surrounded by dotted lines in FIG. 2 are not generally used in Japanand are used only for data transmission using push buttons.

FIG. 3 shows transmission conditions for transmitting signals to selecta line by a phone number represented by the DTMF signals. Thecombination of the two frequencies and the transmission conditionsproduces DTMF signals that are scarcely produced in nature and can beclearly discriminated from natural sounds such as voices. Therefore, theDTMF signals and ordinary broadcast audio signals in a multiplexbroadcasting mode and the receiver is able to separate the DTMF signalscomparatively easily from the broadcast audio signals. A multifunctiontelephone uses DTMF signals to reproduce, or initiate play back ofmessages recorded by an automatic answering telephone set installed atone location by operating the push buttons of a push-button telephoneset at a place away from the one location to record or reproduce aresponse message recorded on the automatic answering telephone set andto erase messages recorded on the automatic answering telephone set.

Broadcasting of a Plurality of Pieces of Secondary Broadcast Information

The sending side, i.e., the broadcasting station, uses the functionsignals "A", "B" and "C" among the function signals "A", "B", "C" and"D", which are not used for PB circuit selection, for indicating secondbroadcast information transmission start information, and uses thefunction signal "D" as transmission termination signal. Since there arethree kinds of transmission start information, three kinds of secondbroadcast information can be discriminated. When broadcasting the threekinds of second broadcast information, each of the three kinds of secondbroadcast information is demarcated with one of the function signals"A", "B" and "C", and the function signal "D". For example, informationnecessary for responding to a two-way broadcast program, such as thephone number of an accepting telephone circuit, second broadcastinformation representing a transmission rate is broadcast between atransmission start information, i.e., the function signal "A", and thetransmission termination information, i.e., the function signal "D",environment setting second broadcast information representing, forexample, a restriction on the last significant digit of the phone numberof the responding side and current time-of-day setting, is broadcastbetween the functional signals "B" and "D", and information aboutclearing received data is broadcast between the functional signals "C"and "D" in a multiplex broadcasting mode.

The receiving side receives numerical values, symbols and data betweenthe function signal "A", "B" or "C", and the function signal "D" as asecond broadcast data row (information group), and stores the secondbroadcast data rows separately in predetermined storage areas of astorage device, which will be described later.

To give a receiver of interactive television standards version 00 accesspermission to access an accepting phone number "0990-1234-1234" at atransmission rate of 300 bps, second broadcast information representedby a data row of the function signals, "00#0990*1234*1234" demarcatedwith the function signals "A" and "D", is transmitted as response accessinformation in combination with main broadcast audio signals in amultiplex broadcasting mode. In this data row, "00" before "#" indicatesinteractive television standards version 00, and numerical datafollowing "#" indicates the accepting phone number. To give a receiverof interactive television standards version 01 access permission toaccess an accepting phone number, "0990-1234-1235" at a transmissionrate of 1200 bps, a data row of the function signals,"01#0990*1234*1235" demarcated with the function signals "A" and "D" istransmitted as response access information in combination with mainbroadcast audio signals in a multiplex broadcasting mode. In this datarow, "01" before "#" indicates interactive television standards version01 (transmission rate: 1200 bps) and numerical data following "#"indicates the accepting phone number. In those data rows representingresponse access information, the symbol "#" is a separator indicating abreak between individual data, and the symbol "*" is a pause symbolindicating a pause.

To limit access qualification to only particular phone numbers(subscriber numbers) or TV viewers having particular equipmentidentification numbers, a data row demarcated with the function signals"B" and "D" is transmitted in combination with main broadcast audiosignals in a multiplex broadcasting mode. For example, to give phonenumbers the last significant digits of which are "0" access permissionto gain access, a data row, "0#0" demarcated with the function signals"B" and "D" is transmitted in combination with main broadcast audiosignals in a multiplex broadcasting mode. To give phone numbers the lastsignificant digits of which are "1" access permission to gain access, adata row "0#1" demarcated with the function signals "B" and "D" istransmitted in combination with main broadcast audio signals in amultiplex broadcasting mode. In these data rows, the numeral "0" beforethe symbol "#" indicates that access permission to gain access is givento phone numbers or identification numbers having the last significantdigits equal to the numeral following the symbol "#". To give numbersthe last significant digits of which are even numbers access permissionto gain access, a data row, 0#0*0#2*0#4*0#6*0#8 demarcated with thefunction signals "B" and "D" is transmitted in combination with mainbroadcast audio signals in a multiplex broadcasting mode. In this datarow, the symbol "*" indicates logical sum (OR).

To provide time data for presetting the TV receiver for future picturerecording, a data row demarcated with the function signals "B" and "D"is transmitted in combination with main broadcast audio signals in amultiplex broadcasting mode. For example to provide time data indicatingthe current time-of-day, 7:00 a.m., Dec. 15, 1993, Tuesday, a data row,"1#1993121520700" demarcated with the function signals "B" and "D" istransmitted in combination with main broadcast audio signals in amultiplex broadcasting mode. When a broadcast program is to be broadcastbetween 7:00 a.m. and 7:29 a.m. on next Sunday, a data row,"10#07000729" demarcated with the function signals "B" and "D" istransmitted. When another broadcast program is to be broadcast between12:00 a.m. and 2:15 p.m. on next Monday, a data row "11#12001415"demarcated with the function signals "B" and "D" is transmitted. Inthese environment setting data row, the symbol "#" is a separatorindicating a break between individual data and the symbol "*" indicates"OR (logical sum)".

To clear, for example, number restriction, i.e., receiving data clearinginformation, a data row, "99#0" demarcated with the function signals "C"and "D" is transmitted. To clear accepting phone number, a data row,"99#1" demarcated with the function signals "C" and "D" is transmitted.

Thus, the function signals "A", "B", "C" and "D", which are not used astelephone circuit selecting signals, are used as the transmission startinformation and the transmission termination information in transmittingsecond broadcast information. Therefore, even if a DTMF sound istransmitted on a scene of a drama in which a phone call is made, theDTMF sound will not be mistaken for the sound of phone call, and thesecond broadcast information can be surely transmitted and received.

A TV set oriented to two-way broadcast programs, i.e., a multiplexbroadcast receiver, in a preferred embodiment according to the presentinvention will be described hereinafter with reference to FIGS. 1, 1A,4, 5 and 6. Referring to FIG. 1, the TV set comprises a signal system 10and a control system 20 for controlling the signal system 10. Broadcastwaves received by an antenna 1 is transferred to a tuner 11. The tuner11 selects the broadcast signals of a desired channel specified by achannel selection signal given thereto from the control system 20,converts the selected broadcast signals into intermediate frequencysignals, and then gives the intermediate frequency signals to anintermediate frequency circuit 12 comprising a video demodulator 13 andan audio demodulator 14. The intermediate frequency circuit 12demodulates video signals and audio signals. Video signals S13 providedby the video demodulator 13 is transferred through a video signalprocessor 15 to a picture tube 16. A sound multiplex decoder 17 decodesaudio signals S14 provided by the audio demodulator 14 and providesbilingual signals or stereophonic signals SR and SL. Amplifiers 18R and18L amplifies the signals SR and SL and gives the amplified signals SRand SL to a right loudspeaker 19R and a left loudspeaker 19L,respectively.

The audio signals S14 provided by the audio demodulator 14 istransferred also through a preprocessor 31 to a DTMF decoder 32. TheDTMF decoder 32 continuously searches the input signals for DTMF signalsincluded in the input signals. Upon the detection of a DTMF signal, theDTMF decoder 32 decodes the DTMF signal; that is, numerals "0" to "9"and symbols "#", "*" and "A" to "D" are decoded. Data obtained bydecoding the DTMF signal is given to the control system 20. The DTMFdecoder 32 may be a widely used DTMF decoder available on the market.The preprocessor 31 is used for preprocessing the DTMF signal to enablethe DTMF decoder 32, even if the same is an ordinary DTMF decoderavailable on the market, to decode the DTMF signal in a high accuracy.The preprocessor 31 serves as a filter circuit that removes frequencycomponents other than the DTMF signal from the audio signals S14 to givethe DTMF decoder 32 an input signal that can be satisfactorily decodedby a DTMF decoder available on the market.

The TV set is provided with a MODEM 33 for data communications to dealwith two-way broadcast programs, such as programs involving TV viewers.The MODEM 33 has a circuit terminal LINE connected to a telephonecircuit 2, and a telephone terminal TEL connected to a telephone set 3.The MODEM 33 is connected to the system bus 200 of the control system20. The output signals of the MODEM 33 is given to the DTMF decoder 32,and the DTMF decoder 32 decodes DTMF signals transmitted through thetelephone circuit 2 and gives decoded DTMF signals to the control system20.

The control system 20 comprises a CPU 21, a ROM 22, a DRAM 23, a SRAM 24and a VRAM 25, which are connected to the system bus 200. Stored in theROM 22 are control programs including a DTMF data receiving andprocessing program, and fonts graphic data for display. The DRAM 23serves as a working storage principally for arithmetic operations, theSRAM 24 stores setting information about the TV receiver and IDinformation, and VRAM 25 stores data for display.

The control system 20 further has I/O ports 261, 262, 263 and 264, and aVTR control port 27. Control signals are transferred through the I/Oport 261 to the video signal processor 15 and the sound multiplex datadecoder 17. A remote control signal receiver 35 receives remote controlsignals, such as infrared remote control signals, transmitted by aremote controller 34. A remote control signal decoder 36 decodes theinput remote control signals and the decoded remote control signals aretransferred through the I/O port 261 to the control system 20. The CPU21 executes a control operation specified by operating the remotecontroller 34, according to the control programs stored in the ROM 22.For example, when the remote controller 34 is operated for channelselection and sound volume control, tuning and sound volume control areexecuted and, at the same time, font data necessary for displayingcharacters and symbols is read from the ROM 22 and is transferred to theVRAM 25. Then, the data provided by the VRAM 25 is combined with thevideo signals S13 to display the data on the screen of the picture tube16 for an appropriate period of time, for example, in a superposed mode.The data for channel selection and sound volume control is stored in thenonvolatile SRAM 24 every time the data is provided to select the samechannel and the same sound volume for the so-called last memory functionwhen the main switch is turned on again after the main switch has beenturned off.

A channel selection signal is given through the I/O port 263 to thetuner 11. In this embodiment, time data provided by a timer circuit 37for real-time indication and an interrupt operation at predeterminedtime is transferred through the I/O port 264 to the control system 20.In this embodiment, three VTRs VTR1, VTR2 and VTR3 are controlledthrough the VTR control port 27. The control system 20 gives controlsignals to the VTRs and receives status signals from the VTRs throughthe VTR control port 27 to control the VTRs for desired controloperations. Each of the VTRs is internally provided with a tuner and anintermediate frequency circuit and is connected, for example, through adistributor to the antenna 1. The control system 20 controls the VTRsfor preset picture recording operations. Referring to FIG. 1A, a blockdiagram of a broadcast multiplex transmitter is shown in which atransmitter section is depicted as element 4, a means for generating asecondary broadcast signal is depicted as element 5, a means forgenerating primary broadcast information is depicted as element 6, and amultiplexer is depicted as element 7. In any case,

Reception and Processing of Multiplex Information Operations of the TVreceiver of FIG. 1 for receiving and processing multiplex informationwill be described hereinafter with reference to FIGS. 4 and 5.

While the TV receiver is in operation, the preprocessor 31 and the DTMFdecoder 32 continuously monitor the audio signal S14 of a broadcastprogram on the selected channel to search the audio signal S14 for DTMFsignals. The CPU 21 monitors the output signal of the DTMF decoder 32received through the I/O port 262 continuously or periodically in step101. Upon the detection of a DTMF signal in the audio signal S14 of thecurrently received broadcast program in step 102, the DTMF decoder 32decodes the DTMF signal and the output decoded signal D32 representingthe numerals and the symbols of the DTMF decoder 32 is given to the CPU21 in step 103. In step 104, a checking operation is executed to see ifthe DTMF signal meets transmitting conditions, such as the duration ofthe DTMF signal is 50 msec or above, a pause between the end of the DTMFsignal and the start of the following signal is 30 msec or above, andthe sum of the length of the DTMF signal and the pause is 120 msec orabove to avoid receiving error data due to radio disturbance and toprevent mistakenly receiving the same frequency components as the DTMFsignal accidentally included in ordinary sounds. If it is decided instep 104 that the received data is not that of a DTMF signal, thetemporary storage area of the DRAM 23 is cleared and a save pointer isinitialized in step 105, and then the program returns to step 101. If itis decided in step 104 that the received data is that of a DTMF signal,a query is made in step 106 to see if the save pointer address is withina temporary storage area. In a state where the TV receiver has been justturned on or the TV receiver is in an error state, the save pointeraddress is outside the temporary storage area and the response in step106 is negative. Therefore, an address in the temporary storage area isinitialized for the pointer for resetting in step 107 to prevent writingdata in the DRAM 23 with an address indicated by the save pointerundefined, causing malfunction or the run-away of the software. If it isdecided in step 106 that the pointer address is within the temporarystorage area or after an address in the temporary storage area has beeninitialized for the pointer in step 107, a query is made in step 108 tosee if the received data consists of the numerals "0" to "9" and thesymbols "#" and "*". If the response in step 108 is affirmative, a queryis made in step 109 to see if there is any free space in the temporarystorage area. If the response in step 109 is affirmative, i.e., if thepointer indicates an address within the temporary storage area, thereceived data ("0" to "9", "#", "*") is stored in the address indicatedby the pointer in the DRAM 23 in step 110, the pointer is updated by onecharacter in step 111, and then the program returns to step 101 torepeat the steps for checking the DTMF signal. If the response in step109 is negative, i.e., if there is not any free space in the temporarystorage area, an error procedure is carried out in step 112 to clear thetemporary storage area and an address in the temporary storage area isinitialized for the pointer.

If the response in step 108 is negative, i.e., when the received data isnot represented by the numerals "0" to "9" and the symbols "#" and "*",the received data is one of the function signals "A", "B", "C" and "D"corresponding to the aforesaid four function signals. Then, a segmentstorage routine shown in FIG. 5 is executed in step 120. In step 121,the leading address of the temporary storage area is set for thepointer, and then queries are made sequentially in steps 122, 123 and124 to see if the received data is the function signal "A", "B" or "C".If it is decided in step 122 that the received data is the functionsignal "A", in step 125, "A" is set in the address indicated by thepointer. If it is decided in step 123 that the received data is thefunction signal "B", "B" is set in step 126 in the address indicated bythe pointer. If it is decided in step 124 that the received data is thefunction signal "C", "C" is set in step 127 in the address indicated bythe pointer. After the step 125, 126 or 127 has been executed, theprogram returns to step 111 to update the pointer by one character.Then, the program returns to step 101 to repeat the steps for checkingthe DTMF signal.

When all the responses in steps 122, 123 and 124 are negative, it isdecided that the received data is the function signal "D", and then thedata stored in the temporary storage area by that time is processed asone data row (information group).

Since the broadcasting side transmits the function signal "A", "B" or"C" as a transmission start signal when transmitting a DTMF signal,function signal "A", "B" or "C" is stored in the leading address of thetemporary storage area after steps 125 to 127 have been executed.Therefore, a query is made in step 128 to see if the character datastored in the leading address of the temporary storage area is "A", "B"or "C". If the function signal "A" is stored in the leading address ofthe temporary storage area, a data row in a portion from the leadingaddress to the last address indicated by the pointer is stored in acorresponding storage area Ga in step 129. If the character data "B" isstored in the leading address of the temporary storage area, a data rowin a portion from the leading address to the last address indicated bythe pointer is stored in a corresponding storage area Gb in step 130. Ifthe character data "C" is stored in the leading address of the temporarystorage area, a data row in a portion from the leading address to thelast address indicated by the pointer is stored in a correspondingstorage area Gc in step 131. These storage areas Ga, Gb and Gc are setin the DRAM 23 or the SRAM24, which will be described later.

In step 132, the received data row is evaluated and analyzed. If theinformation stored in the storage area Ga, Gb or Gc is a command whichmust be executed in receiving signals, a procedure corresponding to thecommand, such as a procedure for partly or completely clearing thereceived data, a procedure for setting the timer for the currenttime-of-day or a procedure for selecting a menu to be displayed, isexecuted, and then the program returns to step 101 to repeat the stepsfor checking the DTMF signal.

The foregoing multiplex data receiving procedure monitors the audiosignal of a broadcast program continuously, regards a data rowdemarcated with the function signals "A" and "D", "B" and "D" or "C" and"D" as one piece of information, segments the information according tothe type of the information, and automatically stores the segments ofthe information in separate storage areas Ga, Gb and Gc to classify andstore the received information. For example, the received signal isregarded as information connected with accessing a two-way program andis stored in the storage area Ga when the data row starts with thefunction signal "A", the received signal is regarded as informationconnected with environment setting and is stored in the storage area Gbwhen the data row starts with the function signal "B", and the receivedsignal is regarded as information connected with clearing received dataand is stored in the storage area Gc when the data row starts with thefunction signal "C".

Temporary information for dealing with a two-way program, such as theinformation connected with response access, may be cleared upon thereception of a number clear signal. However, since it is possible thatthe channel is changed before the reception of the clear signal, it isdesirable to clear old numbers when the TV receiver is turned off.Therefore, the information connected with response access may be storedin the DRAM 23; that is, the storage area Ga may be set in the DRAM 23.The information connected with environment setting includes time datafor use in presetting the TV receiver for future program reception orfuture picture recording, and the time data of the selected program mustbe stored for a comparatively long period of time, such as one week.Accordingly, it is preferable to store the information connected withenvironment setting in the nonvolatile SRAM 24. In this embodiment, thestorage areas Ga, Gb and Gc are set in the volatile DRAM 23 or thenonvolatile SRAM 24 according to the characteristics of data to bestored therein, such as the term of storage and the mode of clearing.When carrying out a response procedure by a simple interactivetelevision receiver using an ordinary telephone circuit, necessaryinformation including the phone number and communications conditions canbe automatically read from the storage area Ga in the DRAM 23. Whenpresetting the TV receiver for future picture recording, the timeinformation of the selected program transferred from the storage area Gbin the DRAM 23 to the SRAM 24 can be automatically used.

Automatic Response Procedure for Two-way Broadcasting

An automatic response procedure to be carried out by the TV receiver ofFIG. 1 will be described with reference to FIG. 6. Referring to FIG. 6,the remote controller 34 is operated to send a control signal to theremote control signal receiver 35 in step 141, and a query is made instep 142 to see if the received control signal is a response commandinstructing the TV receiver to respond to a two-way broadcast program,such as a quiz program involving TV viewers. If the received controlsignal is, for example, an ordinary command instructing the TV receiverto change the channel, an operation specified by the received controlsignal is carried out in step 140. When the control signal is a responsecommand, a query is made in step 143 to see if access informationincluding an accepting phone number and transmission rate has beenreceived and the access information has been stored on the DRAM 23 bythe signal receiving procedure of FIGS. 4 and 5. If the response in step143 is negative, an error icon or an error message indicating that anyaccess information has not been received is displayed on the screen ofthe picture tube 16 for a fixed time in step 144. If the response instep 143 is affirmative, a query is made in step 145 to see if there isany call limiting information and a query is made in step 146 to see ifthe call limiting conditions are satisfied. The call limiting conditionspecifies, for example, the last significant digit of the ID number orthe phone number of the TV viewer stored on the SRAM 24. The TV viewerhaving the specified last significant digit is inhibited from making acall. When such a limiting condition applies to the TV viewer, a massageis displayed to that effect on the screen of the picture tube 16 for afixed time in step 147. When there is no limiting condition or when theTV viewer falls under a limiting condition, response information isproduced by adding the ID number of the TV viewer to responseinformation, a transmission rate is set according to addressinformation, and the response information is transmitted through theMODEM 33 to the predetermined phone number stored on the DRAM 23 in step151. In step 152, a query is made to see if the transmission issuccessful, the telephone circuit is disconnected in step 153 whentransmission is completed normally, and a message is displayed to thateffect on the screen of the picture tube 16 for a fixed time in step154. If transmission is unsuccessful, a message is displayed to thateffect on the screen of the picture tube 16 for a fixed time in step155.

The broadcasting side is able to control the quantity of responses fromTV viewers by placing a restriction, such as a last significant digitlimitation, on the qualification of responding TV viewers to carry outtwo-way broadcasting easily. The TV viewers are able to make a responsesurely and easily by automatically using the access informationreproduced from the received signal.

Generally, the phone number of the telephone set 3 connected to theMODEM 31 is used as the ID number of the TV viewer, it is also possibleto use a number set during production, such as the number of a BSdecoder, as an ID number. An ID number peculiar to each TV receiver,such as "SONY-01-23456789", is added to an answer, such as "#1", to aquestion made in a quiz program involving TV viewers. The broadcastingside is able to identify the maker of the TV receiver that is qualifiedfor accessing the broadcasting side from the ID number peculiar to theTV receiver and to use the information thus acquired for determiningroyalty payment information for telephone charge.

Since this embodiment multiplexes the DTMF signal representingprogram-related information and the audio signal of a broadcast program,the receiving side is able to employ an inexpensive circuit, such as amass-produced DTMF receiving IC chip, as the DTMF decoder, and TVreceivers provided with such an inexpensive DTMF decoder are lessexpensive than TV receivers oriented to character multiplexbroadcasting. This audio multiplex broadcasting system, differing fromthe character multiplex broadcasting system, is capable of dealing withvarious broadcasting systems by using the same circuit and does notinfluence the conventional broadcasting systems. As is obvious fromperiod of the DTMF signal, the transmission rate of this embodiment ison the order of eight characters per second, which is far lower than thetransmission rate of the character multiplex broadcasting system.However, the quantity of the necessary information is small, no problemwill arise even if the transmission rate is not very high.

The current time-of-day, and time information for presetting the TVreceiver for future program reception or for future picture recordingcan be represented by a data row demarcated with the function signal "B"as a transmission starting signal and the function signal "D" as atransmission termination signal, and the data row of the DTMF signalsystem can be broadcast in the multiplex broadcasting mode. Accordingly,the timer can be simply corrected and the TV receiver can be simply setfor future program reception by using the time information. For example,when the transmitted time information includes correct currenttime-of-day, correction of time-of-day indicated on the timer circuit 37or the time-of-day clock of the VTR, or setting of the timer circuit 37or the time-of-day clock of the VTR for correct time-of-day can beeasily achieved by using the time information. For example, when thetime information is received, the clock of the timer circuit 37 is setautomatically for the correct time-of-day included in the received timeinformation.

When the broadcasting side broadcasts a preview of a program andbroadcasting time information of the program simultaneously by a DTMFsignal system in a multiplex broadcasting mode and the receiving sidereceives the broadcast DTMF signal representing the preview and thebroadcasting time information, data representing the broadcast startingtime and the broadcast terminating time of the previously announcedprogram is stored automatically in the storage area Gb of the DRAM 23,and the data representing the broadcast starting time and the broadcastterminating time is transferred to and stored as future picturerecording data on the SRAM 24 when the presetting button of the remotecontroller 34 is depressed within a fixed time interval. In this case,the channel selection data corresponding to a currently selected channelis written in the SRAM 24 and the channel selection data is used also asfuture picture recording data. Upon the arrival of the broadcaststarting time of the program for which the TV receiver was setpreviously, the timer circuit 37 executes an interrupt operation tostart the VTR connected to the control port 27 for picture recordingoperation. Upon the arrival of the broadcast terminating time of theprogram, the timer circuit 37 executes an interrupt operation again tostop the VTR to terminate the picture recording operation for recordingthe program for which the TV receiver was preset. In this picturerecording operation for recording the program for which the TV receiverwas preset, the TV receiver is started and stopped automatically.

Although the foregoing embodiment uses the function signals "A", "B" and"C" as transmission start information indicating the start of secondbroadcast information transmission and uses the function signal "D" astransmission termination information, the assignment of the functionsignals "A", "B", "C" and "D" to transmission start information andtransmission termination information is optional.

For example, the use of the function signal "D" as transmissionstermination information and the use of repeated combinations andrepeated permutations of the function signals "A", "B" and "C" astransmission start information enables the classification of increasedkinds of second broadcast information. The transmission terminationinformation also may be any one of repeated combinations and repeatedpermutation of the function signals.

The transmission start information and the transmission terminationinformation may be combinations of some of the function signals "0" to"9", "#" and "*", or may be combinations of some of the function signals"0" to "9", "#" and "*", and some of the function signals "A" to "D".

Although the present invention has been described as applied to atelevision broadcasting system and a TV receiver for receivingtelevision signals broadcast by the same television broadcasting system,the present invention is applicable also to an AM radio broadcastingsystem, a FM radio broadcasting system, a PCM voice broadcasting system,and receivers for receiving radio signals broadcast by the samebroadcasting systems. As is apparent from the foregoing description,according to the present invention, the broadcasting side constructsprogram-related second broadcast information, such as two-way broadcastaccess data or future program presetting data, by the DTMF signals in anaudio band, and multiplexes the second broadcast information and themain broadcast audio signals and, therefore, the receiving side is ableto receive and decode the second broadcast information easily by using aDTMF decoder. The decoded second broadcast information is stored in astorage means to eliminate the necessity of writing down an accessnumber to be used to access a program involving TV viewers, which isconvenient to the TV viewers.

Since a DTMF encoder available on the market may be employed, and theDTMF signals are superposed simply on main broadcast audio signals, theload on the broadcasting side is smaller than that that is loaded on thebroadcasting side when the second broadcast information is transmittedin a character multiplex mode.

The receiving side is able to extract and decode the DTMF signals easilyfrom the output signal of the audio demodulator by using a DTMF decoderavailable on the market, the receiving set is inexpensive. Furthermore,since the DTMF signals are extracted from an audio signal and decoded,the received signal decoder need not be changed according to thebroadcasting system, which is necessary when a character multiplexbroadcasting system is employed.

Furthermore, when the decoded second broadcast information is stored ina storage device, the stored second broadcast information can be usedfor automatically responding to a two-way program by an automaticdialing method and for presetting the receiver for future programs.

Although the invention has been described in its preferred form with acertain degree of particularity, obviously many changes and variationsare possible therein. It is therefore to be understood that the presentinvention may be practiced otherwise than as specifically describedherein without departing from the scope and spirit thereof.

What is claimed is:
 1. A multiplex broadcast system comprising:abroadcast station; a receiver; said broadcast station including:atransmitter for transmitting a multiplex broadcast signal formed of aprimary broadcast signal and a secondary broadcast signal that is amulti frequency DTMF signal; a multiplexer for multiplexing saidsecondary broadcast signal with said primary broadcast signal; a signalgenerator for generating said secondary broadcast signal; said receiverincluding:an antenna for receiving said multiplex broadcast signal fromsaid broadcast station; a controller; a tuner for selecting a multiplexbroadcast signal of a desired channel in response to a channel selectionsignal from said controller; demultiplexer means for separating saidsecondary broadcast signal from said multiplex broadcast signal of thedesired channel; storage means for storing data represented by saidsecondary broadcast signal; user input means for inputting control data;and a modem device for communicating with a remote station, wherein saidcontroller controls said modem device to initiate and establishcommunications with a predetermined remote station in accordance withcontrol data received from said user input device and said data storedin said storage means and wherein said multi frequency DTMF signalforming said secondary broadcast signal represents a telephone number.2. A multiplex broadcast receiver comprising:a control system; anantenna for receiving a multiplex broadcast signal from a broadcaststation; a tuner for selecting a multiplex broadcast signal of a desiredchannel in response to a channel section signal from said controlsystem; demultiplexer means for separating a secondary broadcast signalfrom said multiplex broadcast signal of the desired channel; storagemeans for storing data represented by said secondary broadcast signal;user input means for inputting control data; and a modem device forcommunicating with remote stations, wherein said control system includesa controller for controlling said modem device to initiate and establishcommunications with a predetermined remote station in accordance withcontrol data received from said user input device and said data storedin said storage means, and wherein said secondary broadcast signalcomprises a multi frequency DTMF signal representing a telephone number.